1. Field of the Invention
The invention relates to comparison systems and more particularly to systems for evaluating similar objects by the comparison of television images.
2. Description of the Prior Art
Prior art systems for evaluating objects by comparing images of the object being evaluated with an image of a similar object known to meet predetermined specifications have tended to utilize either all digital or all analog techniques. The digital system typically digitized the image of the object known to meet predetermined specifications (referred to as the subject member), and the image of the object to be examined to form first and second arrays or numbers. These arrays were compared to detect differences therebetween. These comparisons were normally made by a digital computer and utilized reasonably sophisticated statistical techniques to detect significant deviations from normal. Such systems performed adequately, however they tended to be expensive due to the sophisticated hardware involved. Other systems using analog techniques while usually simple were limited in performance. For example, typical prior art analog systems utilizing TV signals either compared all of the scan lines of the images or a signal line of each image to detect differences therebetween. This placed a severe limitation on the system when it was desirable to compare more than one scan line of the images but less than the whole image.